A dictionary of Proverbs (Oxford Paperback Reference)

If you RUN after two hares you will catch neither
Cf. ERASMUS Adages III. ccxxxvii. duos insequens lepores, neutrum capit, he who chases two hares catches neither.

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  1509 A. BARCLAY Ship of Fools H5 A fole is he.. Whiche with one haunde tendyth [intends] to take two harys in one instant. 1580 LYLY Euphues & his England II. 157 I am redie to take potions . . yet one thing maketh to feare, that in running after two Hares, I catch neither. 1732 T. FULLER Gnomologia no. 2782 If you run after two Hares, you will catch neither. 1880 C. H. SPURGEON John Ploughman’s Pictures 24 If we please one we are sure to get another grumbling. We shall be like the man who hunted many hares at once and caught none. 1981 P. O’DONNELL Xanadu Talisman v. Let’s take things a step at a time. You know what they say. If you run after two hares you will catch neither. "decision and indecision; wanting and having
  

You cannot RUN with the hare and hunt with the hounds
Also used in the metaphorical phrase to run with the hare and hunt with the hounds. In quot. 1546 tytifils comes from Titivil, formerly a common name for a demon.

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  a 1449 J. LYDGATE Minor Poems (EETS) 821 He.. holdeth bothe with hounde and hare. 1546 J. HEYWOOD Dialogue of Proverbs I. x. C3 There is no mo [more] suche tytifils [scoundrels] in Englands grounde, To holde with the hare, and run with the hounde. 1694 Trimmer’s Confession of Faith I I can hold with the Hare, and run with the Hound: Which no Body can deny. 1896 M. A. S. HUME Courtships of Queen Elizabeth xii. Leicester, as usual, tried to run with the hare and hunt with the hounds, to retain French bribes and yet to stand in the way of French objects. 1975 J. O’FAOLAIN Women in Wall v. Clotair’s henchmen say: ‘You cannot run with the hare and hunt with the hounds.’ The peasants have an even clearer way of putting this: ‘You cannot’, they say, ‘side with the cow and the clover’. "choices
  

run see also he who FIGHTS and runs away, may live to fight another day; the LAST drop makes the cup run over; STILL waters run deep; while TWO dogs are fighting for a bone, a third runs away with it; we must learn to WALK before we can run.